The CVS1 study strongly suggested that maternally-inherited mtDNA changes (mutations or polymorphisms) are present in most individuals with CVS and neuromuscular disease (CVS+). Maternal relatives (mother, siblings, maternal aunts/uncles and the maternal grandmother) that share the same mtDNA type are often affected with various disease manifestations, but surprisingly, rarely with CVS. The disease manifestations that these relatives appear to be most predisposed to include migraine headache, depression, irritable bowel, hypothyroidism, hypoglycemia, heart arrhythmias, neurovascular dystrophy (intermittent pain and/or swelling, often in the extremities), and chronic fatigue. Most, but not all, of these diseases involve abnormal function of the autonomic nervous system (dysautonomia); this includes CVS. Siblings also appear to have an increased risk for learning disabilities and attention deficit hyperactivity disorder. It is important to note CVS patients and their maternal relatives neither have, nor do we expect that they will get, all or most of the diseases on this list. Rather, the mtDNA code in some way predisposes (increases the chances) that they may someday get one or more of these diseases. The clinical [Boles et al., 2003] and DNA [Wang et al., 2004] findings from the CVS1 study are published.

http://www.cvsaonline.org/announceupdateCVS3.htm